The invention relates to a method and device for injecting two-phase “gas+solid” CO2 into a transferring gaseous medium.
CO2 is used in many industrial applications: carbonization, pH regulation and neutralization of basic agents are, among others, examples of this. Carbon dioxide may be injected into a liquid medium or a gaseous medium.
CO2 is injected into a liquid medium in gaseous or liquid form as the case may be.
When carbon dioxide is injected into a gaseous medium, the usual solution is to inject it in a gaseous single phase form. Most often delivered in liquefied form and stored in this form in a tank, at a pressure of the order of 14 to 20 bar and a temperature of the order of −35 to −20° C., it is then necessary to vaporize it. This vaporization requires the on-site presence of a vaporizer which involves a high cost, both operationally as well as in investment, whether the energy is of electrical origin or is provided by steam available on-site. Moreover, the gaseous carbon dioxide feed line as well as the associated accessories (gate valves, valves etc.) are bulky and costly. Thus conventional devices for injecting carbon dioxide into a gaseous medium are not optimized and these devices are in particular not suitable in the case of the injection of large quantities of CO2.
The use of CO2 in solid form or as carbon dioxide snow is moreover known for cleaning surfaces.
U.S. Pat. No. 4,747,421 describes the use of solid CO2 in the industrial field of semiconductors for removing a photoresist film on the surface of a substrate.
EP 0 631 846 describes an apparatus designed to produce an aerosol for cleaning the inner surfaces of a tool room.
EP 0 288 263 describes an apparatus for removing small particles on the surface of a substrate using a mixture of solid and gaseous carbon dioxide.
U.S. Pat. No. 4,389,820 describes a machine designed to generate a stream of accelerated sublimable particles for surface descaling. The use of CO2 prevents contamination of surfaces as well as atmospheric pollution.
In addition, FR 2 198 778 describes a method and an apparatus for preparing foundry molds, a method in which gaseous carbon dioxide is used for delivering gaseous components in catalytic quantities, both when the mixture of liquid chemical components is gasified as well as when the quantities of components to be added are adjusted.
However, none of the documents cited relates to the enrichment of a transferring gaseous medium with CO2.